Electronic devices use an antenna system to transmit data and messages to other electronic devices in accordance with wireless protocols. Typically, the antenna system includes a power amplifier and an antenna element. The antenna element is usually arranged to transmit signal containing the data. Prior to transmission of the signal, the power amplifier amplifies the signal.
In a typical scenario, the power amplifier is designed taking into account the loading of antenna element. Usually, the power amplifier is designed for a load of 50Ω. However, the load on the antenna element depends on various factors such as the orientation of the antenna element and the external environment surrounding the antenna element. Due to such variations in the load of the antenna element, the antenna element may draw a large amount of current from the power amplifier, which may damage the power amplifier.
In the present state of technology, in order to limit the flow of large amounts of current through the power amplifiers, power amplifiers with variable gain have been designed. In such power amplifiers, the bias voltage applied to the power amplifier is varied in order to vary the gain of the power amplifiers. Since, current flowing through the power amplifier is directly proportional to the gain of the power amplifier, current flowing through the power amplifier is limited. However, varying the bias voltage may change various characteristics associated with the power amplifier, such as: dynamic range, input impedance, and output impedance. These variations in the characteristics of the power amplifier may, in turn, lead to distortion in the output signal generated by the power amplifier.
Thus, there is a need for an improved technique to limit the amount of current flowing through the power amplifier without distorting the output signal.